This invention relates generally to tools for installing cable ties and, more particularly, to handheld tools that apply tension to such ties and cut off the excess portion of such ties while holding the tie under tension. More particularly, this invention relates to such handheld tools that are capable of generating the higher tensions that are needed to tension and cut off metal, rather than plastic, ties.
Flexible cable ties are well known items. Such ties are used to secure wires, cables, tubing and similar items into tight, neat bundles. Typically, flexible cable ties include a head portion and a tie tail portion extending from the head. In use, the tie tail is looped around the items to be secured and then inserted through the head. A locking or ratcheting mechanism in the head holds the tie tail in the head and secures the tie around the bundle. Preferably, the tie tail is pulled through the head under tension to draw the items to be secured into a tight bundle. Thereafter, the excess portion of the tie tail is clipped off near the head.
Many flexible ties are economically molded of flexible plastic. For some applications, however, plastic has insufficient strength or other drawbacks, and metal ties are used. Metal ties include a flat strap portion and a locking head portion, each of which is made of a strong, durable metal such as stainless steel. As a rule, metal ties are significantly stronger than plastic ties of the same size and are typically pulled to much higher tensions than plastic ties when they are installed.
A variety of tools have been developed to enable workers to install flexible cable ties with speed, uniformity and economy. Generally, such tools function to grip the tie tail portion of the tie after the tie has been looped around the items to be bundled. The tool pulls the tie tail until a predetermined desired tension is achieved after which the tool cuts off the excess portion of the tie tail closely adjacent the head. Such tools greatly simplify the task of properly installing cable ties.
Various handheld tools have been developed to assist in the installation of flexible ties. In one well known form of handheld tool, the tool comprises a pistol or gun-like device having a movable trigger or lever that is squeezed by the operator to pull on the tie tail and thereby tension the tie. The operator continues squeezing the trigger until a predetermined tension is achieved after which a cutting blade adjacent the nose of the tool snaps upwardly to clip off the excess portion of the tie tail. A knob at the rear of the tool allows the worker to adjust or set the tension at which cutoff occurs. Examples of such manually operated handheld tools are shown in the inventors' U.S. Pat. No. 4,997,011, issued Mar. 5, 1991, and U.S. Pat. No. 4,793,385 issued Dec. 27, 1998, commonly owned by the assignee hereof.
Prior handheld tie installation tools have been intended primarily for use with plastic ties or smaller metal ties that are not tensioned to the same high tensions desirable with larger metal ties. Accordingly, such prior tools are not optimally suited for tensioning and cutting off metal ties over the full range of tensions such ties can provide.